Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L67/00—Compositions of polyesters obtained by reactions forming a carboxylic ester link in the main chain; Compositions of derivatives of such polymers
  • C08L67/04—Polyesters derived from hydroxycarboxylic acids, e.g. lactones
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G18/00—Polymeric products of isocyanates or isothiocyanates
  • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
  • C08G18/28—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the compounds used containing active hydrogen
  • C08G18/40—High-molecular-weight compounds
  • C08G18/42—Polycondensates having carboxylic or carbonic ester groups in the main chain
  • C08G18/4202—Two or more polyesters of different physical or chemical nature
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G18/00—Polymeric products of isocyanates or isothiocyanates
  • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
  • C08G18/08—Processes
  • C08G18/10—Prepolymer processes involving reaction of isocyanates or isothiocyanates with compounds having active hydrogen in a first reaction step
  • C08G18/12—Prepolymer processes involving reaction of isocyanates or isothiocyanates with compounds having active hydrogen in a first reaction step using two or more compounds having active hydrogen in the first polymerisation step
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G18/00—Polymeric products of isocyanates or isothiocyanates
  • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
  • C08G18/28—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the compounds used containing active hydrogen
  • C08G18/40—High-molecular-weight compounds
  • C08G18/42—Polycondensates having carboxylic or carbonic ester groups in the main chain
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G2150/00—Compositions for coatings
  • C08G2150/20—Compositions for powder coatings
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G2190/00—Compositions for sealing or packing joints
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G2250/00—Compositions for preparing crystalline polymers

Definitions

• This invention relates to polyurethane compositions useful as adhesives, coatings and sealants.
• Polyurethane compositions are desirable in a variety of applications because of their excellent properties. They can be one-part and two-part solvent-borne systems, water-based systems or 100%-reactive solvent-free adhesive systems.
• the reactive hot melt urethane adhesive systems which combine the rapid set or crystallization times of conventional hot melt adhesives with the high bond strengths of a curing system.
• the reactive hot melt urethane adhesives are solid at room temperature, melt to a viscous liquid when heated to moderate temperatures (82-121°C), and are applied in the molten state. The adhesive then cools to a solid state to provide initial bond strength (i.e., green strength) and additionally, cures on contact with ambient moisture to provide its final bond strength.
• These urethane-based systems are superior to conventional hot melt adhesives which lack resistance to solvents and heat, have lower bond strengths, and which can creep under load because they are non-curing.
• hot melt systems including the urethane-based systems, suffer from the disadvantage of "stringing” or “hairing” during application at dispensing temperatures, especially in automated dispensing equipment.
• stringing or hairing is meant that during application by extrusion, thin threads of the molten system form at the applicator tip when it is removed from the point where the hot melt adhesive has been deposited.
• Hairing is undesirable in many applications such as electronic assembly, because of the contamination it introduces. Additionally, hairing can contaminate the work station and application equipment.
• the present invention overcomes this problem by providing a moisture curable, non-hairing hot melt composition of simple formulation.
• the composition also exhibits improved crystallization rates and possesses high green strength.
• a non-hairing, moisture curable hot melt composition comprising an isocyanate-terminated mixture of two or more hydroxy functional polymers that are solid at room temperature (about 25°C).
• the isocyanate-terminated mixture typically has a number average molecular weight of about 1,000 to 10,000 preferably of about 1,000 to 6,000, and most preferably of about 3,000 to 4,500.
• the mixture preferably forms an essentially non phasing blend at application temperature (about 100°C).
• essentially non phasing is meant that, on visual inspection of the melt, there is no gross separation of the hydroxy functional polymers after extended (e.g., 1 hr.) heating at 100°C.
• Suitable prepolymers with residual isocyanate groups are formed by reaction of (1) a mixture of two or more hydroxy functional polymers wherein the total mixture generally has a combined number average molecular weight of about 1,000 to 10,000, preferably of about 1,000 to 6,000, and more preferably of about 3,000 to 4,500 and (2) a polyisocyanate, preferably a diisocyanate.
• useful hydroxy functional polymers are polyester, polylactone, polyalkylene or polyalkylene ether, polyacetal, polyamide, polyesteramide or polythioether polyols.
• Preferred prepolymers are those based on linear aliphatic or slightly branched polyesters containing primary hydroxyl end groups.
• Other useful polyesters contain secondary hydroxyl or carboxyl end groups.
• the prepolymer is preferably at least partially comprised of crystalline or semicrystalline polyester diols.
• Preferred polyesters have melting points between 30°C and 80°C, most preferred between 40°C and 60°C.
• Amorphous polyesters with glass transition temperatures up to 50°C may be useful in blends at less than 50% total polyester weight.
• liquid polyesters may be useful in blends of polyesters at less than 30% total polyester weight.
• Such preferred polyesters can be prepared by reacting a diol with a diacid or derivatives of diacids.
• polyesters prepared by reacting short chain diols having the structure HO-(CH2) x -OH, where x is from 2 to 8, with diacids having the structure HOOC-(CH2) y -COOH, where y is from 1 to 10.
• useful diols include ethylene glycol, 1,4-butanediol, 1,6-hexanediol; 1,4-cyclohexane dimethanol, neopentyl glycol and 1,2-propylene glycol.
• useful diacids include adipic, azelaic, succinic, and sebacic acids.
• triols such as isophthalic, terephthalic, cyclohexane dicarboxylic acid and phthalic anhydride may also be useful in the preferred polyester synthesis.
• polyesters that are useful in the compositions of the invention are the "Lexorez” series commercially available from Inolex Chemical Co. Specific examples of such resins include Lexorez 1130-30P, Lexorez 1150-30P, and Lexorez 1110-25P. Examples of other commercially available polyesters useful in the invention are the "Rucoflex” series of resins available from Ruco Polymer Corporation.
• polylactone that is useful in the invention is "Tone-0260", commercially available from Union Carbide.
• Component ratios can be determined by the performance properties desired.
• Particularly preferred mixtures of hydroxy functional polymers are:
• the ratio of polyesters employed in the invention can vary in the composition. However, it has been found preferable to employ a weight ratio of first to second polyesters in the range of between about 85:15 to 15:85, more preferably 80:20 to 20:80, most preferably 70:30 to 30:70.
• the polyisocyanates which are reacted with the hydroxy functional polymers to form the prepolymers used in the instant invention can be aliphatic or aromatic.
• they are aromatic diisocyanates such as diphenyl­methane-2,4′-diisocyanate and/or 4,4′-diisocyanate; tolylene-2,4-diisocyanate and -2,6-diisocyanate and mixtures thereof.
• isocyanates include diphenylmethane-4,4′-diisocyanate (MDI) and tolylene-2,4-­diisocyanate/tolylene-2,6-diisocyanate (TDI) and mixtures thereof.
• MDI diphenylmethane-4,4′-diisocyanate
• TDI tolylene-2,4-­diisocyanate/tolylene-2,6-diisocyanate
• Isocyanate-functional derivative(s) of MDI and TDI may be used, such as liquid mixtures of the isocyanate-­functional derivative with melting point modifiers (e.g., mixtures of MDI with polycarbodiimide adducts such as "Isonate 143L", commercially available from the Dow Chemical Co., and “Mondur CD”, commercially available from Mobay Chemical Corp.; small amounts of polymeric diphenylmethane diisocyanates, preferably 10% or less by weight of the total isocyanate component, (e.g., "PAPI", and the series “PAPI 20" through “PAPI 901", commercially available from the Dow Chemical Co., "Mondur MR", “Mondur MRS”, and “Mondur MRS-10", commercially available from Mobay Chemical Corp., and “Rubinate M”, commercially available from ICI Chemicals, Inc.); and blocked isocyanate compounds formed by reacting aromatic isocyanates or the above-described isocyanate-­functional derivatives with blocking agents such
• the isocyanate should be present in the prepolymer composition in an equivalent amount greater than that of the hydroxy containing component.
• the equivalent ratio of isocyanate to hydroxyl is preferably from about 1.2 to about 10 to 1.0 and especially preferably from about 1.6 to 2.2 to 1.0.
• compositions of the invention can contain other ingredients or adjuvants if desired.
• chain extension agents e.g., short chain polyols such as ethylene glycol or butanediol
• fillers e.g. carbon black, metal oxides such as zinc oxide, and minerals such as talc, clays, silica, silicates, and the like
• thermoplastic resins plasticizers
• antioxidants pigments
• U.V. absorbers adhesion promoters
• adhesion promoters such as silanes, and the like
• These adjuvants generally comprise up to 50 weight percent of the composition either individually or in combination.
• compositions can contain an effective amount of catalyst or reaction accelerator such as tertiary amines, metal-organic compounds, co-curatives such as oxazolidine, and the like.
• catalyst or reaction accelerator such as tertiary amines, metal-organic compounds, co-curatives such as oxazolidine, and the like.
• Dibutyltin dilaurate is a preferred metal organic catalyst.
• An effective amount of metal-organic catalyst is preferably from about 0.01 to 2 percent by weight of the prepolymer. More preferably, the catalyst is present at a level of about 0.05 to about 1 percent, based on the weight of the prepolymer.
• the adhesive compositions of the invention may be prepared by mixing the components at elevated temperature, using conventional mixing techniques. It is preferred to mix the components under anhydrous conditions. Generally, preparation of the adhesive is done without the use of solvents.
• the hot melt compositions of the invention achieve their initial, or green, strength through crystallization, then continue to cure by exposure to water, e.g., water vapor or moisture.
• water e.g., water vapor or moisture.
• High humidity and heat will provide an accelerated rate of cure while low humidity (e.g., 15% R.H. or less) will provide a slower rate of cure.
• composition of the invention is preferably essentially non-phasing
• some separation of the polyester components is acceptable.
• degree of phasing can be adjusted by varying any or several of certain factors. For example, the degree of chain extension of the polyester, the molecular weight of the polyester and the choice of isocyanate all influence phase separation. For example, as the molecular weight of the polyester decreases, the compatability of the blend increases. Additionally, as the NCO
• compositions of the invention can be employed in any application where a high-performance adhesive, coating, or sealant is desired. They can be applied to a variety of articles and substrates, such as thermoplastic materials, thermosetting materials, foam material, wood, paper, leather, rubber, textiles, non-woven materials and bare and painted metals.
• Viscosity determinations were made using a Brookfield RVF Viscometer and #27 spindle at 121°C. at 10 rpm or 20 rpm. Number average molecular weights (Mn) were determined by end group analysis.
• the following examples show the correlation between isocyanate-terminated polymer mixtures and polymer mixtures not reacted with isocyanate.
• the polymer mixtures are not reacted with the isocyanate for ease of handling.
• Blends were prepared by manually stirring the components at a temperature of about 120°C until well mixed, which was about 10 minutes. The presence or absence of hairing was determined by a visual inspection by observing if "hairs" of liquid adhesive form when a spatula contacting the surface of a melted sample was removed from that surface. If there were no "hairs", the composition was deemed to be non-hairing. This method correlates to application out of a hot melt applicator.
• Table 3 Example No. Parts PHA Parts PEA Parts PBA Parts PCP Non-Hairing 10 50 50 yes 11 50 50 no 12 50 50 no 13 50 50 yes 14 50 50 no 15 100 no 16 100 no
• Examples 24-37 illustrate the effect of varying the ratio of the amount of individual polyesters in the mixture.
• the blends were prepared using the same technique as in Examples 10-16. The results are shown in Table 5.
• Table 5 Ex. No. Parts of PHA Parts of PEA Non-Hairing 24 100 no 25 100 no 26 95 5 no 27 90 10 no 28 85 15 no 29 80 20 borderline 30 75 25 yes 31 70 30 yes 32 50 50 yes 33 25 75 yes 34 20 80 borderline 35 15 85 no 36 10 90 no 37 5 95 no
• Blends of polyesters in a 1:1 ratio by weight were prepared and tested for non-hairing using the following test method:
• the 0.20 cm diameter end of a 14.6 cm long wooden dowel contacted the surface of a sample whose temperature was 121°C and was drawn away from that surface using an electric motor at a speed of 12 cm/second over a distance of 10.2 cm. If the adhesive "trail" from the dowel end was less than 7.6 cm long as it was being removed from the sample surface, the sample was deemed non-hairing. If it was more than 7.6 cm long, the sample was deemed to be hairing.
• Results are set out in Table 6 below.
• a is the number of -CH2- groups in the diol used to form the first polyester
• b is the number of -CH2- groups in the diacid used to form the first polyester
• c is the number of -CH2- groups in the diol used to form the second polyester
• d is the number of -CH2- groups in the diacid used to form the second polyester.
• PESu polyethylene succinate
• Mn 3740 PEA polyethylene adipate
• Mn 4489 PESe polyethylene sebacate
• Mn 4172 PBSu 1,4-polybutylene succinate
• Mn 5318 PBA 1,4-polybutylene adipate
• Mn 3741 PBSe 1,4-polybutylene sebacate
• Mn 3856 PBAz 1,4-polybutylene azelate
• Mn 3704 PHSu 1,6-polyhexamethylene succinate
• Mn 3591 PHA 1,6-polyhexamethylene adipate
• Mn 3741 PHSe 1,6-polyhexamethylene sebacate
• Polyester blends (1:1 ratio) and their non-hairing properties are set out in Table 7 below, where in addition to the abbreviations used in examples 38-82, the following abbreviations are used.
• PNA polyneopentyl adipate
• Mn 2953 CHDMA 1,4-polycyclohexanedimethyl adipate
• Mn 3262 PCP poly ⁇ -caprolactone
• Mn 3033 PPA 1,2-polypropylene adipate
• Mn 2373 Table 7 Ex. No.
• Blends were prepared as in Examples 1-7. In addition to the viscosity and non-hairing (determined as in Examples 1-7) measurements, the blends were tested for degree of phase separation and ability to hold a sustained load.

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• 1989
  • 1989-04-27 NO NO89891754A patent/NO891754L/no unknown
  • 1989-04-28 DE DE68924197T patent/DE68924197T2/de not_active Expired - Fee Related
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